Mixing System

ABSTRACT

A liquid transport system including a bag adapted to hold fluids, the bag being constructed of a flexible fabric. The bag has a top portion, a bottom portion and a sidewall portion forming an interior and exterior. The system includes a discharge port, a fill port and a series of injector ports on the bag providing fluid access to the interior of the bag from the exterior, where each of the ports are sealingly closable. The discharge port and the fill port are adapted to allow product to flow into and out of the bag, and the injector ports are adapted to accommodate an injector probe.

This application is a divisional of U.S. patent application Ser. No.11/326,738, filed on Jan. 6, 2006, which was a continuation applicationclaiming the benefit of and priority to PCT/US2005/021567 filed on Jun.17, 2005 and U.S. Provisional Patent Application Ser. No. 60/616,691filed on Oct. 7, 2004 which is incorporated by reference herein in itsentirety.

FIELD OF INVENTION

This invention relates to bulk fluid container bags, and methods toempty filled bulk fluid container bags.

BACKGROUND OF INVENTION

Many fluids are transported in bulk containers, such as ISO tanks andshipping containers, railcar containers, 55 gallon drums and other bulkcontainers. Highly vicious fluids and fluids high in solids contentpresent particular transportation problems, such as ease of discharge ofa filled container.

Examples of high solids content fluids include pepper mash, fruit pulps,grape mash/musk, drilling muds, clay slurries, fish slurries, tomatoproducts, inks, and paints. During transportation, a high solids contentfluid can separate into a fluid portion and a solids portion. Uponarrival at the discharge location, the solids separation must beaddressed. If the solids portion is dense, the solids will settle to thebottom of the container, requiring removal of the fluids from the topportion of the container and solids removal later. If the solids portionis light, the solids will float to the top and create a solids cap.While the liquid portion is easily discharged from the bottom of thecontainer, the solids cap will remain and must be physically unloadedlater. Unloading of the solids can be labor intensive, such asphysically breaking up and shoveling the solids cap or solids bottom. Toassist in unloading containers filled with high solids content,mechanical agitation has been utilized, such as by placing rotors, vanesor other types of mechanical agitators in the transport tank, or evenrotating the entire container (see U.S. Pat. No. 3,132,846, incorporatedherein by reference).

Air injection has also been a method of mixing (see U.S. Pat. No.4,595,296 to Parks, incorporated herein by reference). In the Parkspatent, a fluid filled tank has a gas injector (or injectors) fixed tothe bottom of the tank connected to a distribution manifold within thetank. The injectors are attached to a source of suitable gas (air,nitrogen or other inert gas), and the gas pulsed into the injectorsassist in fluidizing and homogenizing the liquid/solids stored in thetank. The gas injector generally includes a feed line and an accumulatorplate positioned at the exit of the feed pipe to assist in shaping thereleased bubble shape.

Examples of highly vicious fluids include oils/lubricants, syrups, andresins. These types of fluids present discharge problems due to theinability of these fluids to easily flow, resulting in long dischargetimes. Discharge times can be decreased by heating the fluid, therebylowering the viscosity and increasing the fluid flows. Generally, eitherthe bottom of the container or the entire container will be heated.However, heat transport in a viscous fluid can be slow and inefficient,and hence, smaller containers, such as a 300 gallon container, are usedto reduce the fluid volume to be heated. Even with these smallercontainers, heat times and discharge times can still be excessive.

In certain circumstances, it is desirable to transport fluids inflexible bags in a fixed wall container. A disposable bag preventsdamage/contamination to the transport container from the fluid andeliminates the need to clean the container after each use. For instance,transport bags are used to reduce the potential for tank contaminationof the product when the transported fluid is food stuffs or food gradematerials. In these instances, a transport bag can be constructed offood grade plastics and if needed, can be pre-sterilized prior to use.Additionally, transport bags can be used when transporting hazardousmaterials, thereby preventing contamination of the tank by the fluid.Bag transport of high solids fluids or vicious fluids, however, presentsproblems, as prior art mechanical agitation or air injection isgenerally not feasible due to the inability to position the agitationdevice into the interior of the bag.

SUMMARY OF INVENTION

A liquid transport system includes a bag adapted to hold fluids, the bagbeing constructed of a flexible fabric. The bag has a top portion, abottom portion and a sidewall portion forming an interior and exterior.The system includes a discharge port, a fill port and a series ofinjector ports on the bag providing fluid access to the interior of thebag from the exterior, where each of the ports are sealingly closable.The discharge port and the fill port are adapted to allow product toflow into and out of the bag, and the injector ports are adapted toaccommodate an injector probe. The system includes injector probes andan air injector controller to control the timing/sequence and durationof the injected sequence.

OBJECTS OF INVENTION

It is an object of the invention to provide a mixing system fortransport containers that allows mixing internal to the containerwithout a mechanical agitator.

It is an object of the system to provide a disposal bag for use intransport containers that provides a liner or bag and a means of mixingwithin the liner or bag.

It is an object of the invention to provide for transporting anddischarging high solids content and high viscosity fluids.

It is an object of the system to provide a system for mixing withinjected air within a mixing bag.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view schematic of a transport bag utilizing airinjection.

FIG. 2 is a top view schematic of a 20 foot ISO transport bag showingthe location of various ports on the bag.

FIG. 3 is a side view schematic of an injector probe.

FIG. 4 is an exploded view of an injector fixture.

FIG. 5A is a top view schematic of a transport bag showing the locationsof various ports.

FIG. 5B is a side schematic view of the bag in FIG. 5A depicting themixing currents generated at one injector location.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Shown in FIG. 1 is a bag 1. Bag 1 is not self supporting and requires atransport container or transport structure for support when filled. Bag1 is constructed of liquid impervious fabric, such as a suitable plasticor an elastomer, and should be thick enough to stand the rigors oftransport and resist inadvertent puncture. For transport of pepper mash(up to 80% solids), a 40 mil bag manufactured of polyethylene has beenfound suitable. Bag size can vary depending on the transport supportstructure that will be used to transport the filled bag. By transportcontainer is meant a container or frame adapted to hold the appropriatesized bag where the bag is adapted to be transported or shipped, anddoes not refer to a fixed mixing facility container. A common transportcontainer is an ISO shipping container used in bulk marine transport.ISO shipping containers are manufactured in standard sizes. The standardwidth of ISO containers is 8 feet, the standard heights are 8 feet 6inches, and 9 feet 6 inches, and the most common lengths are 20 feet and40 feet. Less common lengths include 24, 28, 44, 45, 46, 48, 53, and 56feet.

Bag 1 has a top portion 2, a bottom portion 3, and side walls portion 4.In construction, bag 1 can be a cylinder shaped container manufacturedfrom a blown plastic cylinder with the ends sealed. Alternatively, bag 1can be manufactured from a single sheet that is rolled into an opencylinder with the seam sealed, and the cylinders ends subsequentlyclosed and sealed, such as by heat welding, solvent welding, or othermeans known in the art. The bag 1 could also be constructed frommultiple sheets welded into a rectangular shape or other shape, but suchis not preferred as the additional welds or joints present additionalpotential leakage points.

Located on the top portion of bag 1 is at least one injection port 10.Injection port 10 is a location (port) on the top portion of the bagthat can be opened after the bag has been filled and is adapted tosealingly accommodate an air or gas injection means (the injected gascan also vary depending on the application; inert gases, such asnitrogen, could be used when contact with oxygen could promote unwantedbacterial growth). A suitable injection port 10 includes an opening inthe bag 11 sealed with a fitting 20. One type of an injection port 10used is shown in FIG. 4.

This injection port 10 is located at opening 11 in the bag 1. Positionedaround the bag opening 11 is a seal member 12. As shown, seal member 12is a 90 mil circular sheet of polyethylene heat welded to the bagmaterial. Seal member 12 strengthens the area of the bag in surroundingthe opening 11. If the bag is sufficiently tear resistant, the sealmember 12 can be eliminated. Seal member 12 has an opening 13 whichaligns with the bag opening 11. As shown in FIG. 4, openings 11 and 13are about 2½ inches in diameter. Positioned at the injector port 10 is afitting 20.

One embodiment of the fitting 20 is two inter-mating parts; here a maleand female threaded fitting with a passageway through the fittings, morefully described in U.S. Pat. No. 3,531,142 (incorporated herein byreference). As shown in FIG. 4, fitting 20 has a female member 21 and amale member 22 that are threaded together through the aligned openings11 and 13, thereby compressing and sealing against the seal member 12.If required, a gasket member 16 could also be used to assist in sealing.As shown, the male member 22 also has internal threads to accommodate athreaded plug 23 in order to close and seal the passageway through thefitting 20. Suitable fittings are made of stainless, polypropylene, PVCor other rigid material, and can be obtained from Banjo Corporation ofCrawfordsville, Ind. The threaded plug 23 is a standard 2 inch PVC plug.A threaded cap could be used to seal the passageway if the fitting weredesigned to accommodate a cap.

Other types of fitting connectors could be used in the injector port,such compression or quick connect fittings. Also, instead of a two piecefitting, the fitting could be a one piece closure, designed to mate witha structure molded onto the seal member 12 (such as an upstandingtreaded cylinder molded onto the seal member 12). However, a two piecefitting 20 is preferred for disposable bags, as such a fitting 20 can beremoved from the bag to be cleaned and re-used on another bag. With atwo piece fitting, the fittings should be installed onto the bagmaterial prior to closing the ends of the bag because the interior isnot easily accessed after bag assembly.

The bag 1 can have a series of injection ports 10. Bag 1 also includes asealable fill port 30, and can include a sealable vent port 35 and asealable discharge port 40. The fill port 30 is generally positioned onthe top portion of the bag 1, such as the center of the top portion,while the discharge port 40 is generally located on the sidewall nearthe bottom portion of the bag. The discharge port 40 and fill port 30can be the same port, but this is not preferred when it is desired tore-circulate product prior to or during discharge of product from thebag, as later described. The fill port 30 and discharge port 40 aregenerally larger than the injection port 10 in order to accommodateproduct flows. For instance, for a bag designed for a 20 foot ISOcontainer used to transport pepper mash product, a three inch diameterfill and discharge port have been used. If desired, the bag 1 could beequipped with several fill 30 or discharge ports 40. These ports can beconstructed similarly to an injection port 10 or with other designsknown in the art.

During filling, the fill port 30 is coupled to a product feed line, andproduct is pumped through the line and into the bag through the fillport 30. Once the bag 1 is suitably full, the product feed line isremoved and the fill port 30 is sealingly closed. Feed lines anddischarge lines can be attached to the appropriate port with clamps,quick connects, threaded fittings, or other connectors know in the art.

Discharge port 40 is a sealable port on the bag 1 that couples to adischarge line to allow product to be removed from the bag through thedischarge port 40. The discharge port 40 may be attached to thedischarge line through a valve body or a fitting incorporating a valvebody 41, such as a gate valve, to allow controlled release of product.An appropriate valve can be built into the discharge port 40.Additionally, a “T” or “Y” type splitter fitting 43 may be coupled tothe discharge port 40, as shown in FIG. 2, to create separate dischargepaths and allow for recirculation of a portion (or all) of thedischarged product, thereby assisting in mixing. The splitter fittingmay be equipped with a suitable valve or valves to control flow andapportion flow through the separate discharge paths. In lieu of asplitter fitting, a second discharge port 40 could be used for productrecirculation as later described.

Positioned on the top of the bag 1 is a vent port 35 (an injection port10 could be used as a vent port 35). Vent port 35 allows the user tobleed off unwanted gas pressure within the bag during filling,discharging or mixing. The vent port 35 may be constructed similarly toan injection port 10 or of other construction known in the art. Ventport 35 may be coupled to a pressure actuated device, such as a springloaded check valve, to keep the air pressure within the bag 1 at orbelow a predetermined maximum value.

Injection ports 10 are adapted to accommodate an injector probe 50 attime of product discharge. Injector probes 50 are pipes, tubes or otherair passageways with suitable fittings to sealingly couple to theinjection port 10. Air injector probes 50 are inserted into theinjection ports 10, and connected to a source of suitable gas forinjection into the product, generally through an air injection line. Thefully installed probe 50 will be almost as long as the bag is high, asthe distal end of the probe 50 should be located near the floor of thebag (for pepper mash, 4-12 inched off the floor, with 6 inches beingpreferred).

Installation of a full length injection probe 50 in the closedenvironment of a transport container containing a filled product bag canbe difficult, and hence, the injector probe 50 may be assembled insections joined with suitable couplings 52, such as a threaded coupling.One embodiment of an injector probe 50 is shown in FIG. 3, showing apipe 51 constructed of 1 inch PVC, having a male threaded fitting 55adapted to mate and seal with injector fitting 20 shown in FIG. 4.Fitting 55 could be a female threaded fitting, quick connect, or otherconnection means. The fitting also keeps the lower end of the injectorprobe at its desired location by resisting the upward forces caused byair injection through the distal end of the probe 50.

An alternative design for the injector probe 50 is to build the probeinto the injector port 10. For instance, a flexible tubing slightlylonger than the bag height could be utilized as the injector probe. Oneend of the flexible tubing would be fixedly connected to the interiorfloor portion of the bag and the other end of the tube would beconnected to a corresponding injection port 10, such as through aninjector fitting 20. The flexible tubing may be opened at the bottom, orclosed with an opening in the side of the tubing at a desired heightabove the bottom of the floor portion. In this fashion, the bag 1 couldbe shipped with injector probes 50 installed, and it is only necessaryto connect an air line to the injection ports at the discharge site toinitiate mixing.

Use of the Bag

The following operation will be described using a bag 1 having a singleinjection port, vent port, discharge port and fill port. For small bags,a single injection port may be suitable (for instance, a 300 gallon bag)but for larger bags, multiple injection ports are preferred. It ispreferred that an injection port 10 be located near the discharge port40.

The bag 1 is shipped empty to the fill location. The empty bag iscollapsed, and is generally flat or may be folded to create a smallerfootprint for shipping. At the fill location, the bag 1 is positionedwithin the transport container with all ports. The bag 1 is generallystill in a collapsed state, but pick up loops may be attached to theexterior of the bag 1 to allow for attachment of the bag 1 onto thetransport container. A fill line is attached to the fill port 30, andproduct then released or pumped through the fill line into the bag 1.The vent port 35 may need to be opened to allow venting of gases in thebag 1 while filling. Alternatively, prior to filling the bag 1 withproduct, the bag could be “inflated” by attaching a gas injector line toan injection port 10 and filling the bag with a suitable gas to ease thefilling process. Once the bag is suitably full, filling stops, the fillline removed, and all ports sealed closed for transport. If the shippingcontainer is a closed container where the top is not removable, it ispreferred that either the bag height be less than that of the containerheight, or alternatively, that the filling stop before the bag is full.Space is required between the container top and bag top to allow anoperator to climb into the transport container onto the top portion ofthe filled bag to access the ports on top of the bag, for instance, toremove and attach hoses, close ports, or other desired actions.

At the discharge facility, the container is opened and an operatorclimbs onto the bag 1 and opens the fitting 20 at the injection port 10and inserts an injector probe 50. For a multi-piece injector probe (forinstance a two section probe), the operator would insert the bottommostsection into the injector probe 50, and the top section would then bethreaded onto the bottom section, and the top section also inserted. Thethreaded coupling on the top section of the injector probe 50 is thentreaded onto the fitting 20 at the injection port 10, sealing the probe50 into the port opening. If the liquid phase of the product is in thetop portion of the bag 1, it may be desired to inflate the bag prior toinstallation of the injector probes to avoid loss of fluid. This may beaccomplished by attaching an air line (without a probe) to an injectionport 20, injecting air and hence inflating any slack in the bag (keepingthe vent port closed). If the solids have formed a cap on top of theliquids, the operator will have to force the probe 50 through the solidslayer. To assist, the probe's distal end may be shaped to assist inpiercing a solids cap.

Once the probe 50 is inserted, an air line or gas line 70 is attached tothe injector probe 50. Each air line is connected to a valve, and thevalves are connected to an air distribution manifold, and gas injectionis begun. The values are operated by a controller 60 to control thecycling and duration of the air pulses to the injection ports 10.Suitable controllers are available from Pulsair Systems, Inc. inBellevue Wash. To bleed off excess gas pressure, the vent port 30 isopened. While gas injection can be continuous, it has been found thatpulsing gas into the system is generally more efficient. Further, whileall injection ports/probes could be pulsed simultaneously (such as byhaving the air feeder lines tie into a common air distribution line) itis preferred to pulse each probe sequentially. For instance, a preferredpulsing pattern is to pulse from the back of the bag (furthest from thedischarge port) to the front of the bag.

Gas is pulsed into the bag through the probe, and enters the productnear the bottom of the bag. The rising air mixes the product and willbreak up the solids layer. After a suitable mixing period, a fairlyhomogeneous mixture is obtained, and the discharge port 40 can beopened, and product removed. Air injection may continue or cease duringproduct discharge, dependent upon the product's characteristics. Forinstance, it may be advantageous to continue air injection for productwhich quickly separates, particularly injecting air near the dischargeport 40 to avoid clogging of the discharge port.

Product fluids may also be re-circulated during mixing and/ordischarging. Recirculation pumps product about the system to speed themixing of the product to more rapidly achieve a fairly homogeneousproduct. Recirculation can be achieved by attaching a fluidrecirculation line to a port on the bag. Generally, the recirculationline has one end attached to the discharge port 40, and the other endattached to a fill port 30 or an injector port 20 (henceforth referredto as a recirculation port). The recirculation line may be attached tothe discharge port 40 by coupling to one end of a splitter fittingpositioned on a discharge port 40. It is preferred that a gate valve orother valve is used to control flows through the two available paths ina splitter fitting. A pump then is actuated to draw product throughrecirculation system.

The bag 1 shown in FIG. 2 is a 20 foot ISO container bag having sixinjection ports positioned on the top portion of the bag. Each injectionport accommodates a two inch coupling shown in FIG. 4, and availablefrom Banjo Corporation. Notice that one injection port 10A is located sothat an injector probe 50 can be placed near the discharge port 40. Thedischarge port 40 accommodates a three inch opening, as does the fillport 30. The bag 1 shown in FIGS. 5A and 5B are also designed for a 20foot ISO container bag, having 5 injector ports, a 2 inch recirculationport, and a 2 inch vent port.

The controller 60 can be configured to accommodate a variety of pulsedurations and cycle times. For instance, a Pulsair PLC controller systemwas used for air injection of pepper mash in a 20 foot ISO bag containerconfigured similarly to that shown in FIGS. 5A and 5B. The mash had beenstored in the bag for some period, and a solids cap had been formed. Theair injection parameters are as follows: air pressure was maintainedthrough a regular to about 80-90 PSI. Each injector was pulsed 55 pulsedper minute (PPM) with a pulse time (dwell time) of 0.5 seconds.Recirculation at 60 gallons per minute was performed simultaneously withair injection. The injectors were pulsed sequentially, in a pattern fromthe back to the front. After one hour of mixing, the bag was emptied,and product recovery was in excess of 90%.

Injected air creates rising bubbles in the product, inducing a currentin the fluid, thereby locally mixing the product. Each injector sitewill have a local area of influence that is the volume surrounding theinjection site affected by the induced current, as depicted in FIG. 5B.It is preferred that the local area of adjacent or neighbor injectorpoints overlap to eliminate dead zones and provide for complete mixing.For pepper mash, a high solids fluid with a solid cap, the area ofinfluence is believed to be a circular area of about 2 to 6 feetdiameter when examined near the top of the bag, with 4 feet beingpreferred. The number and placement of the injection ports 10 will varydepending upon the product characteristics, as well as the injectingparameters. For instance, with a product that has solids which settle,more injectors may be required to ensure adequate coverage at the bottomof the bag. For other types of fluids, the number of injectors, theinjection parameters, mixing times, and the need for recirculation, willvary dependent upon the product's desired discharge characteristics andthe product's characteristics prior to mixing. It is believed thatinjection ports separated by distances of 1-10 feet will be sufficientto cover many typical applications.

For mixing vicious fluids, current techniques include heating theproduct container. Air injection increases the speed of heat transportin the fluid, and hence, decreases the time to raise the temperature ofthe product to the desired temperature. In fact, if the injected air isheated prior to injection, the current method of directly heating thecontainer can be eliminated.

The bag, injector probes, transport container and air injection systemprovide a fluid transport system capable of dealing with high solids orhigh viscosity fluids. Although the present invention has been describedin terms of specific embodiments, it is anticipated that alterations andmodifications thereof will no doubt become apparent to those skilled inthe art which are intended to be included within the scope of thefollowing claims.

1. A liquid transport system comprising a bag adapted to hold fluids,said bag constructed of a flexible fabric, said bag having a topportion, a bottom portion and a sidewall portion forming an interior andexterior; said bag having a discharge port, a fill port and a series ofinjection ports providing fluid access to said interior of the bag fromsaid exterior of said bag, where each of said ports being sealinglyclosable and said discharge port and said fill port are adapted to allowproduct to flow into or out of said bag, and each of said injectionports are adapted to accommodate a gas injector probe.
 2. The liquidtransport system of claim 1 further having a transport container forsaid bag, where said bag is adapted to fit within the interior of saidtransport container.
 3. The liquid transport system of claim 1 furtherhaving a gas injection system, where said gas injection system includesa series of injector probes, said injector probes adapted to be insertedinto and sealingly coupled with said injection port, said injectorprobes having a tubular portion having a length suitable to dischargegas through said injector probe near said bottom portion of said bag. 4.The liquid transport system of claim 3 wherein said gas injection systemfurther comprises a series of air lines, each said air line connected toone of said series of injector probes, and a source of gas, each of saidair lines connected to said source of gas.
 5. The liquid transportsystem of claim 1 wherein said injector port includes a seal membersealingly attached to said bag, said seal member having an openingaligned with an opening in said bag, said injector port furtherincluding a fitting to seal said opening in said seal member.
 6. Theliquid transport system of claim 2 where said transport container is anISO transport container.
 7. The liquid transport system of claim 4further including a heater connected to said gas injection system andadapted to heat the gas transported in said air injection system to apredetermined value.
 8. The liquid transport system of claim 1 furtherincluding a recirculation line, said recirculation line fluidlyconnected between said discharge port and said fill or one of saidinjection ports.
 9. The liquid transport system of claim 3 wherein atleast one of said series of injector probes is positioned to inject gasnear the vicinity of said discharge port.
 10. The liquid transportsystem of claim 3 wherein said source of gas is an inert gas.
 11. Theliquid transport system of claim 4 further including a controller, saidcontroller adapted to control the flow of said gas from said source tosaid air lines.
 12. The liquid transport system of claim 1 wherein saidseries of injection ports are positioned on said top portion of said bagand spaced apart to provide effective mixing of product though injectionof gas into product through said injector probes.
 13. The liquidtransport system of claim 12 wherein adjacent injection ports in saidseries of injection ports are separated from one another by a lineardistance in the range of 1-10 feet.
 14. A liquid transport systemcomprising a bag adapted to hold fluids, said bag constructed of aflexible fabric, said bag having a top portion, a bottom portion and asidewall portion forming an interior and exterior; said bag having adischarge port, and an injection port providing fluid access to saidinterior of the bag from said exterior of said bag, where each of saidports being sealingly closable, and said discharge port is adapted toallow product to flow out of said bag, and each of said injection portis adapted to accommodate a gas injector probe.